In the future the biggest problem is over population. Most of this problem can be traced back to one man. An operative has been sent back in time to stop this. The man had 100 children all of whom had 100 children and so on... the plan is to change his DNA (to make him incapable of doing this), but nothing is ever that simple... The boy who will be the "megaplayboy" is Momonari Junta, who throws up whenever he gets ecchi thoughts. Karin, the operative, accidentally changes him into the "megaplayboy" (thus causing the very problem she was sent to solve), now she has to try to correct her mistake.